This invention relates to a puncture sealing composition. It also relates to a puncture sealing composition useful in preventing tires from going flat.
Puncture sealing tubeless tires are known in the art. Most of the tires previously proposed contain, in the area of the tire, called the undertread or the area extending across the crown of the tire from one shoulder to the other, a layer of sealant composition. This composition generally has plastic and adhesive qualities such that the composition tends to stick to a puncturing object and when the puncturing object is withdrawn it tends to flow into the opening or puncture, forming a plug which seals the opening against loss of air from the tires. Unfortunately it has proven difficult to provide a composition which would flow into the puncture hole and yet have sufficient viscosity to prevent it from flowing at elevated temperatures, which may go up to 250.degree. F. in an automobile pneumatic tire under operating conditions. The problem is complicated by the extreme centrifugal force to which the composition is subjected as the tire rotates at high speed, since such centrifugal force tends to cause the composition to flow into the central crown area leaving the area near the shoulders unprotected. Furthermore it has proven difficult to provide a sealant composition which would retain the desired balance of viscosity, plasticity, adhesion and conformability over an extended period of service.
It is therefore an object of this invention to provide a puncture sealing composition which has the ability to seal against puncturing objects on the tire. Another object of this invention is to provide a puncture sealing composition that is useful over a wide range of temperatures. It is another object of this invention to provide a puncture sealing composition that provides uniform protection across the crown of the tire. Other objects of this invention will become apparent from the following disclosure.